GM and GMC
Air Conditioning and Coolant
GMC Yukon
Heating Ventilating and Air Conditioning

Why would the AC light on a 1991 GMC blink but the air conditioner not work?


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2006-07-24 22:58:36
2006-07-24 22:58:36

I had a problem one time with my Chrysler New Yorker. If the power windows would not work then the a/c would not turn on, if I turned the car off and tried the window switch if the window worked the a/c worked. My mechanic said it was a bad ignition switch. He changed it out and no more problems. I believe there may be a code stored in the computer that can be cleared out, if no other problems exist. ----- Here's what you need to do.... (taken from a 4x4 newsboard from "Kevin")

Disconnect the battery negative cable to allow the A/C control module to reset. It has gone into fail safe mode due to excessive cycling of the compressor clutch. Once it is reset you will be able to again run the compressor to diagnose the system. It will go into fail safe if the compressor cycles more than 15 times in one minute or something like that (not exactly sure of the time period). Your compressor will cycle too often if you are low on refrigerant and cause the control module to enter the failure mode. When you reconnect the battery & start the truck, immediately start charging the system with freon.

There is also a known problem with the harness connector to the low pressure clutch cycling switch that can cause the same problem. Many parts supply stores carry the replacement harness connector to fix the problem of poor and intermittent contact at the connector. To test your low pressure cycling switch harness connector, just wiggle it a little bit while the compressor clutch is engaged. If the connector is bad you will notice the clutch cutting in and out as you wiggle the wires going into the connector.


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